Time evolution of the equatorially averaged T–P profile within model A covering the >1500 (Earth) yr of simulation time required for it to reach equilibrium. The light grey dashed line shows the initial temperature profile for P > 10 bar, whilst the dark grey line shows the forcing profile for P < 10 bar. The time evolution is represented by the intensity of the lines, with the least evolved (and thus lowest visual intensity) snapshot starting at t ≈30 yr followed by later snapshots at increments of approximately 60 yr.